The invention relates to a spinning or twisting spindle to be arranged vertically, having a spindle shaft which is disposed in a spindle bearing housing comprising a step bearing and a bolster which is constructed as a roller bearing, the rollers of which are held by means of a roller cage in the circumferential direction, and by means of rims in the axial direction, and with their circumferential surfaces, run on a running surface of an outer ring of the bearing inserted into the spindle bearing housing and on a running surface of the spindle shaft.
In the case of spinning or twisting spindles of the initially mentioned type, there is the problem that, particularly at high rotational speeds, the spindles have the tendency to rise upwards in the vertical direction. The cause of these vertical forces which results in the rising of the spindles is not completely clear. It is conceivable that this rising is caused by the drive, such as a tangential belt which does not move exactly perpendicularly with respect to the spindle shaft. It is probable, however, that the bolsters also contribute to the occurring axial forces, as tests have indicated. The rollers may slope relative to the spindle shaft such an axial upward directed thrust is generated.
It is an object of the invention to provide a spinning or twisting spindle of the initially mentioned type in which the rising in the axial direction is reliably prevented.
This object is achieved in that the rollers are guided in such a manner that, at least when the spindle shaft is rotating, they are aligned diagonally with respect to the axis of the spindle shaft, in which case, with their areas facing away from the step bearing, they move ahead of the areas facing the step bearing, in the rotating direction.
By means of this construction, it is achieved that the rollers exercise an axial thrust on the spindle shaft which is directed toward the step bearing. In this manner, an axial thrust is intentionally generated by means of the bolster which counteracts the rising. Thus it is no longer accidental whether the rollers of the bolsters constructed as a roller bearing participate in forces which may promote a rising of the spindles and it is intentionally provided that the rollers exercise such an axial thrust on the spindle that this thrust is directed against a possible force causing the rising.
In a first embodiment of the invention, it is provided that the roller cage of the bolster is equipped with roller pockets which are aligned diagonally with respect to the axis of the spindle shaft. As a result, the intended diagonal positioning of the rollers is caused by a corresponding guiding by means of the roller pockets of the roller cage. In this embodiment, the rollers are constantly held in this diagonal position so that the direction of the axial thrust is a function of the rotating direction of the spindle. A spindle which is equipped with this type of a roller bearing can therefore be operated only in one rotating direction.
In order to achieve in a further development of the invention that irrespective of the rotating direction of the spindle, an axial thrust is always generated which is directed toward the step bearing, it is provided in another embodiment that the rollers have a shape which tapers in the shape of a truncated cone in the direction of the step bearing. In this embodiment, the rollers will align themselves when the spindle shaft rotates. They place themselves diagonally in each case in such a manner that an axial thrust is generated which is directed toward the step bearing.
In another embodiment of the invention, it is provided that the running surface of the spindle shaft has a shape that tapers toward the step bearing in the shape of a truncated cone. Also in the case of this embodiment, the rollers align themselves with the rotating spindle shaft in such a manner that an axial thrust in the direction of the step bearing is always generated, irrespective of the rotating direction of the spindle shaft.
In another embodiment of the invention, it is provided that the running surface of the outer ring of the bearing has a shape that widens into a step bearing in the shape of a truncated cone. Also in this embodiment, the rollers are taken along by the rotating spindle shaft and are aligned diagonally in such a manner that, irrespective of the rotating direction, an axial thrust is always generated which is directed to the step bearing.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.